Edit File: posix-clock.h
/* * posix-clock.h - support for dynamic clock devices * * Copyright (C) 2010 OMICRON electronics GmbH * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #ifndef _LINUX_POSIX_CLOCK_H_ #define _LINUX_POSIX_CLOCK_H_ #include <linux/cdev.h> #include <linux/fs.h> #include <linux/poll.h> #include <linux/posix-timers.h> #include <linux/rwsem.h> struct posix_clock; /** * struct posix_clock_operations - functional interface to the clock * * Every posix clock is represented by a character device. Drivers may * optionally offer extended capabilities by implementing the * character device methods. The character device file operations are * first handled by the clock device layer, then passed on to the * driver by calling these functions. * * @owner: The clock driver should set to THIS_MODULE * @clock_adjtime: Adjust the clock * @clock_gettime: Read the current time * @clock_getres: Get the clock resolution * @clock_settime: Set the current time value * @timer_create: Create a new timer * @timer_delete: Remove a previously created timer * @timer_gettime: Get remaining time and interval of a timer * @timer_settime: Set a timer's initial expiration and interval * @fasync: Optional character device fasync method * @mmap: Optional character device mmap method * @open: Optional character device open method * @release: Optional character device release method * @ioctl: Optional character device ioctl method * @read: Optional character device read method * @poll: Optional character device poll method */ struct posix_clock_operations { struct module *owner; int (*clock_adjtime)(struct posix_clock *pc, struct timex *tx); int (*clock_gettime)(struct posix_clock *pc, struct timespec *ts); int (*clock_getres) (struct posix_clock *pc, struct timespec *ts); int (*clock_settime)(struct posix_clock *pc, const struct timespec *ts); int (*timer_create) (struct posix_clock *pc, struct k_itimer *kit); int (*timer_delete) (struct posix_clock *pc, struct k_itimer *kit); void (*timer_gettime)(struct posix_clock *pc, struct k_itimer *kit, struct itimerspec *tsp); int (*timer_settime)(struct posix_clock *pc, struct k_itimer *kit, int flags, struct itimerspec *tsp, struct itimerspec *old); /* * Optional character device methods: */ int (*fasync) (struct posix_clock *pc, int fd, struct file *file, int on); long (*ioctl) (struct posix_clock *pc, unsigned int cmd, unsigned long arg); int (*mmap) (struct posix_clock *pc, struct vm_area_struct *vma); int (*open) (struct posix_clock *pc, fmode_t f_mode); uint (*poll) (struct posix_clock *pc, struct file *file, poll_table *wait); int (*release) (struct posix_clock *pc); ssize_t (*read) (struct posix_clock *pc, uint flags, char __user *buf, size_t cnt); }; /** * struct posix_clock - represents a dynamic posix clock * * @ops: Functional interface to the clock * @cdev: Character device instance for this clock * @dev: Pointer to the clock's device. * @rwsem: Protects the 'zombie' field from concurrent access. * @zombie: If 'zombie' is true, then the hardware has disappeared. * * Drivers should embed their struct posix_clock within a private * structure, obtaining a reference to it during callbacks using * container_of(). * * Drivers should supply an initialized but not exposed struct device * to posix_clock_register(). It is used to manage lifetime of the * driver's private structure. It's 'release' field should be set to * a release function for this private structure. */ struct posix_clock { struct posix_clock_operations ops; struct cdev cdev; struct device *dev; struct rw_semaphore rwsem; bool zombie; }; /** * posix_clock_register() - register a new clock * @clk: Pointer to the clock. Caller must provide 'ops' field * @dev: Pointer to the initialized device. Caller must provide * 'release' field * * A clock driver calls this function to register itself with the * clock device subsystem. If 'clk' points to dynamically allocated * memory, then the caller must provide a 'release' function to free * that memory. * * Returns zero on success, non-zero otherwise. */ int posix_clock_register(struct posix_clock *clk, struct device *dev); /** * posix_clock_unregister() - unregister a clock * @clk: Clock instance previously registered via posix_clock_register() * * A clock driver calls this function to remove itself from the clock * device subsystem. The posix_clock itself will remain (in an * inactive state) until its reference count drops to zero, at which * point it will be deallocated with its 'release' method. */ void posix_clock_unregister(struct posix_clock *clk); #endif